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Search results for: STRUT BEARINGS
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Stability and load bearing capacity of a braced truss under upward wind loading
PublicationThe paper is focused on the numerical and experimental investigation of stability of a steel truss under upward wind loading. The structure was stiffened by elastic braces situated at the top and bottom chord. Usually the lateral (translational) brace stiffness is considered. However, the rotational stiffness of braces caused by interaction between torsional stiffness of the truss top chord and bending stiffness of the roof elements...
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Water-lubricated stern tube bearing - experimental and theoretical investigations of thermal effects
PublicationThe paper presents research results of thermal phenomena accompanying operation of a water-lubricated stern tube bearing with axial grooves. Experimental tests revealed, that intensity of forced axial flow has strong influence on bush temperature. Numerical simulations focused on investigation of the thermal phenomena under operation of water-lubricated journal bearing showed, that restricted axial flow promotes backflow of the...
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New Generation of Water lubricated Foil bearing - Numerical Models and Experimental Verification
PublicationIn the paper a new idea of foil water lubricated bearing and methodology of hydrodynamic characteristics calculations is presented. To assesses the theoretical characteristics of these bearings two different computer models were built. First is structural model coupled with fluid model. It takes into account: fluid flow in the deformed fluid gap, specific design of bearing support and friction in bearing support. The second is...
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Common-Mode Voltage and Bearing Currents in PWM Inverters: Causes, Effects and Prevention
PublicationIn modern induction motor drives an increase of transistors' switching frequency and a decrease of switching times are the sources of some serious problems. The high dv/dt and the common mode voltage generated by the inverter PWM control results in the appearances of bearing currents, shaft voltages, motor terminal overvoltages, the decrease of motor efficiency, and electromagnetic interference. The aspects of common mode (CM)...
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Effects of loading pattern and lubricant pressure influence on bearing alloy fatigue characteristics
PublicationOpisano wyniki testów zmęczeniowych przeprowadzonych dla stopu łożyskowego AlSn (11,3 Cu 1,2) osadzonego na taśmie stalowej. Doświadczalnie określono wartości obciążeń niszczących dla różnych warunków obciążenia: dla obciążeń zginających wahadłowych, dla obciążeń zginających wahadłowych przy równoczesnym działaniu słabego lub zmiennego ciśnienia w komorze olejowej.
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Modeling of bearing capacity of footings on sand within stochastic micro-polar hypoplasticity.
PublicationAnalizowano numerycznie efekt wstępnego rozkładu wskaźnika porowatości na wytrzymałość i strefy ścinania w problemach fundamentów na piasku w skali modelowej. Obliczenia wykonano przy zastosowaniu stochastycznej metody elementów skończonych i mikropolarnego modelu hipoplastycznego. Wskaźnik porowatości miał formę skorelowanych pól stochastycznych. Dodatkowo obliczono efekt skali dla 3 różnych szerokości fundamentów.
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WATER LUBRICATED MAIN SHAFT BEAR INGS WITH THREE LAYER BUSH – MODERN SOLUTION FOR MARINE INDUSTRY
PublicationWater lubricated sliding bearings are increasingly popular in marine and hydro power industry. Such popularity is partly due to their simple construction which also means a relatively affordable price. Properly designed and installed water lubricated bearings may well last for over a decade. During the last decade their traditional range has been expanded with new, modern products like three layer bearing bush. The work presents...
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Modeling of acoustics of hearing aid earmold systems
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Waveguide modeling as a tool for fitting a hearing aid
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Digital hearing aid with time and spectral transposition.
PublicationNastępstwem uruchomienia w Polsce, prowadzonych na szeroką skalę, badań przesiewowych słuchu jest konieczność zaoferowania pomocy osobom cierpiącym na niedosłuch poprzez leczenie i protetykę słuchu. Tymczasem, aktualnie oferowane rozwiązania aparatów słuchowych nie są w stanie sprostać niektórym specjalistycznym potrzebom aparatowania, m. in.: najmłodszych dzieci, osób pracujących w hałasie, pilotów wojskowych oraz osób korzystających...
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Waveguide model of the hearing aid earmold system
PublicationBackground The earmold system of the Behind-The-Ear hearing aid is an acoustic system that modifies the spectrum of the propagated sound waves. Improper selection of the earmold system may result in deterioration of sound quality and speech intelligibility. Computer modeling methods may be useful in the process of hearing aid fitting, allowing physician to examine various earmold system configurations and choose the optimum one...
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Waveguide model of the hearing aid earmold system
PublicationBackground The earmold system of the Behind-The-Ear hearing aid is an acoustic system that modifies the spectrum of the propagated sound waves. Improper selection of the earmold system may result in deterioration of sound quality and speech intelligibility. Computer modeling methods may be useful in the process of hearing aid fitting, allowing physician to examine various earmold system configurations and choose the optimum one...
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Hearing aid operating in acoustical free field
PublicationAparatowanie bardzo małych dzieci (od 5 miesiąca życia) za pomocą standardowych protez słuchu natrafia na wiele trudności natury praktycznej. Dotyczy to procesu dopasowania aparatu słuchowego, czyli doboru jego ustawień stosownie do aktualnych charakterystyk ubytku słuchu dzieci. Tymczasem wczesne aparatowanie jest zagadnieniem o ogromnym zanczeniu dla rozwoju słuchu, mowy i ogólnej inteligencji dziecka. Referat prezentuje uzyskane...
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Loudness Scaling Tests in Hearing Problems Detection
PublicationThe number of people using portable audio players has increased significantly over the recent years. This implies the rise in the number of people having hearing loss problems. Therefore, there is a need to find appropriate procedures that simplify the process of the hearing problem detection. Investigations performed show that audiometric tests may not be sufficient to assess hearing in young people. Contrarily, the obtained results...
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Poroelastic Material for Urban Roads Wearing Courses
PublicationConventional road materials used for producing wearing courses of roads are based on mineral aggregate and bituminous or Portland cement binders. The road materials must be optimized for different properties, including skid resistance, durability, rolling resistance and tire/road noise. Unfortunately, it seems that within classic technologies it is very difficult to achieve further reduction of tire/road noise. Innovative porous...
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Poroelastic Material for Urban Roads Wearing Courses
PublicationConventional road materials used for producing wearing courses of roads are based on mineral aggregate and bituminous or Portland cement binders. The road materials must be optimized for different properties, including skid resistance, durability, rolling resistance and tire/road noise. Unfortunately, it seems that within classic technologies it is very difficult to achieve further reduction of tire/road noise. Innovative porous...
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Expert media approach to hearing aids fitting
PublicationW artykule zaprezentowano problematykę dopasowania protez słuchu. Przedstawiono system ekspercki, który pozwala na znalezienie charakterystyk aparatu słuchowego adekwatnego do uszkodzenia słuchu. System został oparty o metodę zbiorów przybliżonych i logikę rozmytą.
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Speech recognition system for hearing impaired people.
PublicationPraca przedstawia wyniki badań z zakresu rozpoznawania mowy. Tworzony system wykorzystujący dane wizualne i akustyczne będzie ułatwiał trening poprawnego mówienia dla osób po operacji transplantacji ślimaka i innych osób wykazujących poważne uszkodzenia słuchu. Active Shape models zostały wykorzystane do wyznaczania parametrów wizualnych na podstawie analizy kształtu i ruchu ust w nagraniach wideo. Parametry akustyczne bazują na...
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Internet-based automatic hearing assessment system
PublicationCelem referatu jest prezentacja systemu przesiewowego badania słuchu w oparciu o Internet. Wady słuchu stanowią jedną z najszybciej postępujących chorób we współczesnym społeczeństwie. W tym kontekście ważne staje się umożliwienie przeprowadzania masowych testów wykrywających ubytki słuchu. Przedstawiona aplikacja zawiera audiometryczny test tonalny, test ilustrowany dla dzieci oraz test rozumienia mowy w szumie. Po zakończeniu...
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Szacowanie liczby roszczeń w działalności towarzystwa ubezpieczeniowego w oparciu o metodę zagospodarowania poniesionych strat
PublicationW publikacji omawia się znaczenie prognoz w zarządzaniu przedsiębiorstwem, klasyfikacje metod prognozowania ryzyka i szacowania jego wielkości poprzez wykorzystanie prognozy, ryzyko w działalności firmy ubezpieczeniowej, metody ilościowe w szacowaniu ryzyka działalności ubezpieczeniowej i roszczenia. Prezentuje się również przykład wykorzystania metody zagospodarowania poniesionych strat do oszacowania liczby roszczeń.
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Analiza eksperymentalna intensyfikacji transportu ciepła w płaszczowo-rurowym wymienniku ciepła z generatorami strug gazu
PublicationW pracy przedstawiono modelowy płaszczowo-rurowy wymiennik ciepła z generatorami strug gazu wraz z wynikami badań cieplnych. Badania eksperymentalne wykonano dla układu gaz-ciecz. Pomiary prowadzono przy stałych wartościach temperatury czynników na wlocie do wymiennika, tj. w zakresie 120-200 st.C w przypadku powietrza (czynnika grzewczego) i 18 st.C w przypadku wody (czynnika ogrzewanego). Przedstawiono zależności współczynnika...
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Nowoczesne rozwiązania stosowane w kontekście ograniczenia strat energetycznych w budynkach oraz poprawy komfortu cieplnego
PublicationW artykule zaprezentowano nowoczesne rozwiązania pozwalające na zmniejszenie energochłonności budynków oraz ograniczenie wpływu warunków atmosferycznych na komfort cieplny. Omówiono metodologię optymalizacji kształtu oraz rodzaju materiałów wykorzystywanych w procesie powstawania budynków użytkowych. Zaprezentowano tu metody oparte o najnowsze zdobycze techniki takie jak materiały budowlane z domieszką PCM (ang. Phase change materials)
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Modele teoretyczne i matematyczne momentu strat mechanicznych w pompie wyporowej stosowanej w napędzie hydrostatycznym
PublicationPrzedstawiono modele teoretyczne i matematyczne momentu strat mechanicznych występujących w pompie o stałej teoretycznej wydajności qPt na obrót wału (o stałej teoretycznej objętości roboczej VPt) bądź o zmiennej geometrycznej wydajności qPgv na obrót wału (o zmiennej geometrycznej objętości roboczej VPgv). Modele mają służyć badaniom laboratoryjnym i symulacyjnym strat energetycznych w pompie umożliwiającym ocenę sprawności energetycznej...
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Application of the Optimization Methods to the Search of Marine Propulsion Shafting Global Equilibrium in Running Condition
PublicationFull film hydrodynamic lubrication of marine propulsion shafting journal bearings in running condition is discussed. Considerable computational difficulties in non-linear determining the quasi-static equilibrium of the shafting are highlighted. The approach using two optimization methods (the particle swarm method and the interior point method) in combination with the specially developed relaxation technique is proposed to overcome...
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STUDY IN MECHANICAL FAULT ELEMENT THERMOGRAPHY THROUGH THE MACHINE: The case of deep groove ball bearings of a career without screen.
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Polymer journal bearings behaviour research under limited lubrication and cooling conditions conducted on high torque test rig
PublicationPolymer journal bearings are frequently used as a water-lubricated bearings of small marine units’ propeller shafts . Choice of these bearings is based on their simple construction and relatively low purchase and maintenance costs. Although properly designed and installed water lubricated bearings may well last for over a decade, rapid wear or failure of these bearings can be observed...
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The experimental identification of the dynamic coefficients of two hydrodynamic journal bearings operating at constant rotational speed and under nonlinear conditions.
PublicationHydrodynamic bearings are commonly used in ship propulsion systems. Typically, they are calculated using numerical or experimental methods. This paper presents an experimental study through which it has been possible to estimate 24 dynamic coefficients of two hydrodynamic slide bearings operating under nonlinear conditions. During the investigation, bearing mass coefficients are identified by means of a newly developed algorithm....
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Stability and bearing capacity of arch-shaped corrugated shell elements: experimental and numerical study
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Air journal bearing utilizing near-field acoustic levitation: stationary shaft case
PublicationResults of a study to examine a unique idea of self-levitating journal bearing are presented in this paper. the idea represents a radical departure from the current bearing technology. it utilisesacoustic levitation, which relies on the sound energy radiated by an object supporting a load. acoustic levitation has been demonstrated to support loads of up to 10 kg. in order to support a load theacoustic wave emitted by the radiating...
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Correction to Aromatic Dendrimers Bearing 2,4,6-Triphenyl-1,3,5-triazine Cores and Their Photocatalytic Performance
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Experimental comparison of the transition speed of a hydrodynamic journal bearing lubricated with oil and magnetorheological fluid
PublicationA journal bearing test bench is used to find the transition speed between the hydrodynamic and mixed lubrication regimes for a modified magnetorheological (MR) fluid. It is shown that the transition speed of the bearing can be reduced by applying a local magnetic field near minimum film when it is lubricated with the MR fluid, and that this will only marginally increase friction. The lubricating performance of the MR fluid is compared...
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Methods of deep modification of low-bearing soil for the foundation of new and spare air runways
PublicationAfter analyzing the impact of aircraft on the airport pavement (parking spaces, runways, startways), it was considered advisable to consider the problem of deep improvement or strengthening of its subsoil. This is especially true for low-bearing soil. The paper presents a quick and effective method of strengthening the subsoil intended for the construction of engineering structures used for civil...
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Effect of presence of lifting pocket on the THD performance of a large tilting-pad thrust bearing
PublicationHydrostatic assistance is a commonly used method to improve limited load carrying ability of tiltingpad thrust bearings during transient states of operation of vertical shaft hydro-generators. Despite of special hydraulic equipment (as pumps, valves, etc.), it also requires manufacturing of special recesses/pockets at pad sliding surfaces, into which oil is injected under high pressure. It allows to lift the rotor before start-up...
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Influence of local bush wear on water lubricated sliding bearing load carrying capacity
PublicationOne of main problems concerning water-lubricated bearings is their durability. There are known cases of bearings with life time measured in decades, and some, whose refurbishment was necessary just days after start-up. Obtaining stable fluid film friction plays key role in the durability of these bearings. Unfortunately, their load-carrying capacity is limited due to water's low-viscosity. The conducted experimental...
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Acoustic journal bearing – Performance under various load and speed conditions speed conditions
PublicationThe paper presents results of experimental testing aiming at finding out what effect system of piezo-electric actuators (PZTs)attached to an aerodynamic journal bearing has on the magnitude of shaft's motion within the bearing operating at specified speed and load. The results clearly demonstrate effectiveness of PZTs in mitigating the shaft's motion thus contributing to the increased stability of the bearing. This stabilizing...
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Current-based higher-order spectral covariance as a bearing diagnostic feature for induction motors
PublicationConducting the diagnosis of induction motors remotely by analyzing the supply current is an attractive prospect with the lack of access to the engine. Currently, there is no solution, based on analysis of the current, the credibility of which would allow its use in industry. The statistics of bearing failures in induction motors indicate that they constitute more than 40% of induction motor damage, therefore, bearing diagnosis...
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Improvement of the thrust bearing calculation considering the convectional heating within the space between the pads
PublicationA modern thrust bearing calculation tool should consider not only the oil film between pad and rotating collar but also the space between the pads. The oil flow in the space has a significant influence on the oil film inlet temperature, the convectional cooling of pad and collar and should be included in the bearing calculation methods. The authors use a tool developed at Clausthal University of Technology in cooperation with the...
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Field tests on hydrodynamic and hybrid operation of a bi-directional thrust bearing of a pump-turbine
PublicationIn vertical shaft pump turbines operating in pumped storage power plants an important role is played by a thrust bearing. Because of bi-directional character of operation, thrust bearing tilting pads have to be supported symmetrically, which is known to be unfavourable from the point of view of their performance. Large thrust bearings have to be carefully designed so as to minimise excessive thermo-elastic pad deformations. The...
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Bearing Capacity of aluminum bars with built-up cross section and glued or welded connections
PublicationThe paper is focused on numerical analysis and experimental test of aluminum bars with glued and welded connections between separate members. The connection properties were tested experimentally. The numerical analysis were conducted for the beam and shell model of the structure. The shape and magnitude of initial geometric imperfection was taken into account
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IN VITRO PROPAGATION OF RHODODENDRON TOMENTOSUM - AN ENDANGERED ESSENTIAL OIL BEARING PLANT FROM PEATLAND
PublicationRhododendron tomentosum Harmaja (formerly Ledum palustre L.) is a medicinal peat bog plant native to northern Europe, Asia and North America. This plant has a distinctive aroma thanks to the presence of essential oil, to which it also owes its anti-inflammatory, analgesic, antimicrobial and insecticidal properties. However, in Europe R. tomentosum is classified as an endangered species, mainly due to degradation of peatlands. In...
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STABILITY AND LOAD BEARING CAPACITY OF A BARS WITH BUILT UP CROSS SECTION AND ELASTIC SUPPORTS
PublicationThe present paper is devoted to the numerical analysis and experimental tests of compressed bars with built–up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static...
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Reducing common mode voltage and bearing currents in quasi - resonant DC - link inverter
PublicationIn the paper, a concept of separation of an inverter-fed induction motor drive from its mains supply by two transistor switches inserted in the dc-link circuit is reexamined based on the proposed parallel quasi-resonant dc-link inverter (PQRDCLI). The objective of the paper is to show an advantage of the proposed topology in limiting high frequency common mode voltage and bearing currents. In the laboratory setup, an induction...
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Simulation of large thrust-bearing performance at transient states, warm and cold start-up
PublicationThe start-up of a large hydrodynamic thrust bearing of a vertical hydrogenerator is one of the most critical situations during the lifetime of a bearing. Hydrodynamic load capacity is low due to low speed and higher thermal deformations of the pad. A new approach to the simulation of a hydrodynamic bearing is shown in this article. A combination of finite elements method and computational fluid dynamics is used to perform the transient...
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ANALYSIS OF THE LOAD-CARRYING CAPACITY OF A HYDRODYNAMIC WATER-LUBRICATED BEARING IN A HYDROELECTRIC POwER PLANT
PublicationThe paper presents an analysis of the load-carrying capacity of a historic hydrodynamic water-lubricated radial bearing of an unconventional segment design installed in the Braniewo Hydroelectric Power Plant. The aim of the calculations was to determine whether the bearing operates in the conditions of hydrodynamic or mixed lubrication, as well as to establish the optimal geometry of the axial grooves allowing for the highest load-carrying...
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Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads
PublicationA modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions...
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A facile approach to fabricate load-bearing porous polymer scaffolds for bone tissue engineering
PublicationBiodegradable porous scaffolds with oriented interconnected pores and high mechanical are load-bearing biomaterials for bone tissue engineering. Herein, we report a simple, non-toxic, and cost-effective method to fabricate high-strength porous biodegradable scaffolds, composed of a polymer matrix of polycaprolactone (PCL) and water-soluble poly (ethylene oxide) (PEO) as a sacrificial material by integrating annealing treatment,...
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Effect of the Presence of the Lifting Pocket on The THD Performance of a Large Tilting-Pad Thrust Bearing
PublicationIn this paper, an attempt was taken to study the effect of the lifting pocket on THD performance of a large tilting-pad thrust bearing of Itaipu power plant. B3earing performance was evaluated including recess shape for several cases of its depth. The results show, that hydrostatic recess changes calculated bearing properties quite significantly, especially in the vicinity of the pocket
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Theoretical analysis and experimental tests of tilting pad journal bearings with shoes made of polymer material and low-boiling liquid lubrication
PublicationSelecting the appropriate bearing system for the rotor requires a good knowledge of the available solutions and the operating conditions of the machine. For newly designed machinery operating in adverse conditions, selecting bearings that ensure correct and long-lasting operation can be extremely challenging. Difficulties in- crease when the machine’s operating parameters are beyond the technical capabilities of available technical solutions....
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Computer simulations of hearing aid acoustical system performance
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